Nowadays, powers of conventional electronic devices are provided by an external power source supply or a battery module. In general, when the electronic device is not connected to the external power source, the power of the electronic device is provided by the battery module. When the electronic device is connected to an external power source, the external power source provides power to the system of the electronic device, and charges the battery module. In addition, most users connect the external power source to the electronic device for long-run usage, therefore, the battery module is often charged and continuously maintained at high power capacity. However, such usage may cause the accelerated aging of the battery module, and shorten the lifespan of the battery module. Therefore, an improved power control method is needed.